Ways of controlling traffic at an intersection are, in general, of two kinds, one which by means of erected traffic lights controls cars coming from all directions, helping them take turns passing in a direction at a time, and the other one which, like an expressway, by means of elevated road structures and with no traffic lights, simply leaves cars to pass nonstop through by either the upper or the lower level of roads.
Traffic lights usually delay traffic, often causing grievous congestion. It is desirable, therefore, to have the fewest possible traffic lights or, if ever possible, none at all.
Multilevel intersection systems are better than others, for cars can pass nonstop through without having to wait for the green, but construction of a clover leaf or another similar system demands quite a sizable lot of land and is often found all but impracticable in areas where, as in urban centers, land prices are forbidding. In addition, problems arise at times for drivers when accesses for left and right turns vary from place to place.
The present invention is intended to provide a new intersection system, which uses less land usually required for one and yet is convenient for automobiles to go straight on or turn right or left, either entirely free of interruption by signal lights, or if not entirely free, subject to the least possible interruption.
Another objective of the present invention is to provide an intersection system, which can curtail the time spent by cars awaiting the change of lights.
With a view of attaining these objectives, the present invention provides the three following systems:
(1) System 1 of the present invention comprises two mutually intersecting roads, xe2x80x9cmain roadsxe2x80x9d 1 and 2. At the entrance portion of the intersection, a xe2x80x9cdiverging sectionxe2x80x9d is provided, where the main road diverges in three ways, one for the straight way onward, a second for the right turn, and a third for the left turn; while at the exit portion of the intersection a xe2x80x9cconverging sectionxe2x80x9d is provided for the three ways reaching there to converge into one. In other words, at each diverging section the road branches off in three ways and at the converging section three ways join to become one road.
The main roads are built on two levels at both the diverging and converging sections of an intersection, and when a main road in one direction takes the lower level at the diverging section, it must take the upper level at the converging section, and vice versa. The main roads ascend, or slopes downward at the central section of an intersection, between the diverging and converging sections. If main road 1 is on the upper level at the central section of an intersection, main road 2 takes the lower level there, and vice versa.
Accordingly either one of the two main roads takes the upper and the other the lower at the central section of an intersection, the two crossing each other with a space more than the height of a car in between.
An entrance road, that is, the advancing section, of a main road, is connected, at its converging section at the other end, with the other main road, which intersects the first main road, overhead or beneath it, running in the same direction as that of it.
(2) System 2 of the present invention comprises of two ring-shaped roads, one on the upper and the other on the lower level.
On the outer side of a ring one half-main-road joins each in two given directions, and so does an entrance road each in the other two directions.
On a plan view, the half-main-roads on the upper ring and those on the lower ring, and the entrance roads on the upper and those on the lower respectively run in directions different from each other.
Meanwhile, either more than one of the two one-way roads that constitute a half-main-road or an entrance road, each embody a sloping section, while an entrance road joins with either one of the one-way roads on the lower or upper half-main-road, which runs in the same direction as that of it.
(3) System 3 of the present invention has a plate-shaped road for right turns and another for left turns, added on both the upper and lower levels in the center of the system.
On an edge of each such plate-shaped road, on both the upper and lower levels, a half-main-road joins in each two directions, and an entrance road each in the other two directions.
The half-main-roads on both the upper and lower levels, and the entrance roads of the plate-shaped road on the upper and lower levels, run in directions different from each other, from a plan view, while more than one of the two one-way roads constituting a half-main-road or an entrance road each embody a sloping section. Said entrance roads join with the one-way road of the half-main-road, either on the upper or the lower level, which runs in the same direction.
On each plate-shaped road on the upper or lower level, and on each entering one-way road, a traffic light has to be set up, indeed unavoidably, for the cars coming on from all directions.
Now, in this Specification, a xe2x80x9cmain roadxe2x80x9d means a road consisting of a pair of two straight one-way roads, or one-way road passages which traverse the center of an intersection parallel to each other, in opposite directions. The two one-way roads constituting one main road can be separated from each other, of course, on two levels, one over and the other beneath the other.
An xe2x80x9cone-way road,xe2x80x9d here, means one of the pair of passages that constitute a main road, or a half-main-road, which is shown in the examples of embodiment of the present invention as a single lane, but it can very well be made of two or more lanes.
An xe2x80x9cupper roadxe2x80x9d means a road on a level higher than a lower road on a lower level, and is parallel to the surface of the ground, the height not particularly confined to a certain level; a xe2x80x9clower roadxe2x80x9d means a road which is lower than an upper road and parallel with the surface of the ground, but not necessarily is one that runs on the very ground level.
For instance, to make the length of a sloping section of a road shorter than otherwise, it is possible to build the upper road on an elevated level and the lower road on an underground level.
A xe2x80x9csloping sectionxe2x80x9d means the section of a road that forms a slope to connect an upper and a lower road.
A xe2x80x9ccentral sectionxe2x80x9d means the section of the road that occupies the central part of the intersection system, between its diverging and converging sections.
A xe2x80x9chalf-main-roadxe2x80x9d means, of the main road defined in System 1 of the present invention, either one of the two parts of a main road cut in two by the ring-shaped roads of system 2 or plate-shaped roads of system 3.
An intersection, that is, the part connecting the outer area of an intersection with the ring-shaped road or road plate at one end and the part connecting the ring-shaped road or road plate with the outer area of the intersection at the other end.
As regards the directions, it will be seen that the direction approaching the central section of an intersection system is called the entering direction and that leaving the central section is called the departing direction.